docs: def plot_correlations(self, iabscissa=1):
          """spectrum of correlation matrix and largest correlation"""
          if not hasattr(self, 'corrspec'):
              self.load()
          if len(self.corrspec) < 2:
              return self
          x = self.corrspec[:, iabscissa]
          y = self.corrspec[:, 6:]  # principle axes
          ys = self.corrspec[:, :6]  # "special" values
  
          from matplotlib.pyplot import semilogy, hold, text, grid, axis, title
          self._enter_plotting()
          semilogy(x, y, '-c')
          hold(True)
          semilogy(x[:], np.max(y, 1) / np.min(y, 1), '-r')
          text(x[-1], np.max(y[-1, :]) / np.min(y[-1, :]), 'axis ratio')
          if ys is not None:
              semilogy(x, 1 + ys[:, 2], '-b')
              text(x[-1], 1 + ys[-1, 2], '1 + min(corr)')
              semilogy(x, 1 - ys[:, 5], '-b')
              text(x[-1], 1 - ys[-1, 5], '1 - max(corr)')
              semilogy(x[:], 1 + ys[:, 3], '-k')
              text(x[-1], 1 + ys[-1, 3], '1 + max(neg corr)')
              semilogy(x[:], 1 - ys[:, 4], '-k')
              text(x[-1], 1 - ys[-1, 4], '1 - min(pos corr)')
          grid(True)
          ax = array(axis())
          # ax[1] = max(minxend, ax[1])
          axis(ax)
          title('Spectrum (roots) of correlation matrix')
          # pyplot.xticks(xticklocs)
          self._xlabel(iabscissa)
          self._finalize_plotting()
          return self